How to convert Milliseconds to "X mins, x seconds" in Java?

Question

I want to record the time using System.currentTimeMillis() when a user begins something in my program. When he finishes, I will subtract the current System.currentTimeMillis() from the start variable, and I want to show them the time elapsed using a human readable format such as "XX hours, XX mins, XX seconds" or even "XX mins, XX seconds" because its not likely to take someone an hour.

What's the best way to do this?

Answer 1

Uhm... how many milliseconds are in a second? And in a minute? Division is not that hard.

int seconds = (int) ((milliseconds / 1000) % 60);
int minutes = (int) ((milliseconds / 1000) / 60);

Continue like that for hours, days, weeks, months, year, decades, whatever.

Answer 2

Either hand divisions, or use the SimpleDateFormat API.

long start = System.currentTimeMillis();
// do your work...
long elapsed = System.currentTimeMillis() - start;
DateFormat df = new SimpleDateFormat("HH 'hours', mm 'mins,' ss 'seconds'");
df.setTimeZone(TimeZone.getTimeZone("GMT+0"));
System.out.println(df.format(new Date(elapsed)));

Edit by Bombe: It has been shown in the comments that this approach only works for smaller durations (i.e. less than a day).

Answer 3

Date Time object

Answer 4

I would not pull in the extra dependency just for that (division is not that hard, after all), but if you are using Commons Lang anyway, there are the DurationFormatUtils.

Answer 5

Since 1.5 there is the java.util.concurrent.TimeUnit class, use it like this:

String.format("%d min, %d sec", 
    TimeUnit.MILLISECONDS.toMinutes(millis),
    TimeUnit.MILLISECONDS.toSeconds(millis) - 
    TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millis))
);

Answer 6

DurationFormatUtils worked very nicely. Thanks, Thilo!